Compositions containing quaternary ammonium salts or imidazolinium compounds having at least one long chain hydrocarbyl group are commonly used to provide fabric softening benefits when used in a laundry rinse operation. Numerous patents have been issued for these types of compounds and compositions.
More recently, however, in view of concerns for the environmental safety (e.g., biodegradability) of the quaternary compound softeners, as well as limits in the amounts of these cationic compounds which can be stably incorporated into the more convenient to use liquid formulations, there have been many proposals for partial or total replacements for the conventional "quat" fabric softeners which are exemplified by dimethyl distearyl (or ditallow) ammonium chloride and various imidazolinium compounds.
For instance in GB 2,032,479A, corresponding to EP 038862, to D. Fontanesi (assigned to Albright & Wilson Ltd.) water dispersible unquaternized hydroxyalkyl diamidoamine compounds of formula EQU RNH((CH.sub.2).sub.n NR).sub.m R
wherein an average of from 20% to 80% of the R groups are C.sub.12 to C.sub.22 acyl, at least 20% of the R groups are --CH.sub.2 CH.sub.2 OH or --CH.sub.2 CHOHCH.sub.3 or mixtures of these groups, and any other R group is hydrogen, n is 2 or 3 and m is an integer of from 2 to 5, can be obtained as usable pastes in the presence of lower alkanol solvents. This is stated to be in contrast to partially neutralized unquaternized diamidoamines which, while providing highly effective fabric softening properties, are too viscous even when diluted in the lower alkanol solvents for convenient handling.
U.S. Pat. No. 5,154,838 (corresponding to EP 0459211A2) to Yamamura, et al. (assigned to Kao Corp. ) discloses an aqueous liquid softener composition based on an amidoamine compound which is the condensation reaction product of a di- or tri-amine of formula (I) EQU R.sup.1 NH(C.sub.m H.sub.2m NH).sub.n H (I)
with a fatty acid of formula (II) ##STR1## wherein R.sup.1 represents a straight or branched chain, saturated or unsaturated hydrocarbon group having 8 to 24 carbon atoms, R.sup.2 represents a straight or branched, saturated or unsaturated hydrocarbon group having 7 to 23 carbon atoms, m represents 2 or 3, and n is 1 or 2. These compounds, which are neither hydroxylated or ethoxylated, are noted to have high dispersibility in rinse water, especially when the amidoamine compound is used in the form of its neutral salt.
In U.S. Pat. No. 5,133,885 to L. Contor, et al. (assigned to Colgate-Palmolive Co., the assignee of the present invention) fabric softening compositions are described which are aqueous dispersions of a fatty acid ester quat of formula ##STR2## where one or two R groups represent an aliphatic ester residue of from 12 to 30 carbon atoms of formula --CH.sub.2).sub.n OCOR.sub.4, and the remaining R groups represent lower aliphatic, aralkyl or hydroxyalkyl groups, X.sup.- is an anion and "a" represents the ionic valence of the anion, and a fatty acid amidoamine softener of formula ##STR3## where R.sup.1 is a C.sub.12 to C.sub.30 alkyl or alkenyl group, R.sup.2 represents R.sup.1,R.sup.1 CONH(CH.sub.2).sub.m or CH.sub.2 CH.sub.2 OH; R.sup.3 represents hydrogen, methyl, or (CH.sub.2 CH.sub.2 O).sub.p H, m is a number of 1 to 5 and p is a number of 1 to 5, at a weight ratio of ester quat to amidoamine of from 10:1 to 1:10.
U.S. Pat. No. 4,772,403 to Grandmaire, et al. (Colgate-Palmolive Co.) discloses aqueous fabric softening compositions, especially adapted for use in the rinse cycle of a laundering process. These compounds are based upon (i) cationic fabric softening compounds and (ii) fatty alcohol having an alkyl group of from about 10 to about 22 carbon atoms at an (i)=(ii) weight ratio of from 6:1 to about 2.8:1, and a total amount of (i) and (ii) of 3 to 20 weight percent. A minor amount of water soluble electrolyte and/or an ethoxylated amine can be used as optional ingredients, the latter as an emulsifier to further increase the stability against phase separation of the suspended phase of the formulation.
U.S. Pat. No. 5,108,628 to Uphues, et al. (Henkel) discloses certain aliphatic carboxylic acid amidoamines which are obtained by reaction of polyamines (e.g., diethylentriamine, aminoethyl ethanolamine) with carboxylic acid mixtures containing ether carboxylic acids (R--O--(CH.sub.2 CH.sub.2 O).sub.n --CH.sub.2 COOH, R=C.sub.8-18 alkyl, C.sub.8-18 alkenyl or CH.sub.2 --COOH, n=2 to 20, in combination with aliphatic C.sub.8-22 monocarboxylic acids and/or amide-forming aliphatic C.sub.8-22 monocarboxylic acid derivatives) as fabric softeners stable in the presence of electrolytes.
While these and many other proposals are known for improved fabric softening compositions, nevertheless, still further improvements are desired.